What you need to do for the app review exchange:
- Register on the site.
- Download an application from the Give Point section and comment.
- Take the comment display screen and comment on the application.
If you do, you will earn 1 point.
So you get 1 comment. The more applications you comment, the more comments you get. 
Website: appreviewtransfer.com
How it works : appreviewtransfer.com/how-it-works/